The present disclosure concerns a maser for the generation of coherent electromagnetic waves. Unlike a laser that emits visible light, a maser generates microwaves or radio waves. A maser comprises an active medium, a device for generating a population inversion in the active medium, as well as a resonator that is tuned to the microwave frequency of the maser. Masers are used, for example, in communication traffic with earth satellites, in radio-astronomic reception systems and radio relay systems as amplifiers, for the operation of atomic clocks and as generator for millimeter waves.
In many cases, low temperatures or a high vacuum must be generated to operate a maser. Usually, complex pumping processes such as beam separation, a pump laser or a dynamic nuclear polarization (DNP) are required.